THz Generator Has Highest Signal Quality

MADRID, Dec. 18, 2013 — A terahertz (THz) generator currently in development improves signal quality by 1 million times as compared with the best device of its kind available on the market, opening the technology to applications in biomedicine, transportation safety, industry and radio astronomy, among others.

Terahertz waves, found at the far end of the infrared band, just before microwaves, is a range of the electromagnetic spectrum that has yet to be developed and exploited, say the developers, reseachers at Carlos III University of Madrid (UC3M) and at Luz Wavelabs. Because THz waves can pass harmlessly through the body, they are attractive for security screening applications. Their spectroscopic properties can be used in detecting cancer and other diseases, as well as standoff inspections of potentially hazardous materials.

Researchers at Carlos III University of Madrid and the firm Luz WaveLabs are developing an innovative terahertz generator that improves signal quality by 1 million times as compared to the best device of this kind currently on the market. It will allow the technology to be applied to biomedicine, transportation safety, industry and radio astronomy, among others. Courtesy of UC3M.
Although research into systems that generate and detect THz waves has seen significant advances in recent years, it is still necessary to develop technologies with enough quality, flexibility and ease of use to cause an explosion in the commercialization of the THz range, said Ángel Rubén Criado, a founding partner of Luz WaveLabs.

Luz Wavelabs, which developed out of the university's Department of Electronic Technology with the support of the business incubator Vivero de Empresas in UC3M's science park, is designing high-performance tools that can introduce THz waves to new areas, with the goal of making THz technology into an everyday tool in a few years. The company's star product is the "pure-T-wave," a THz generator that combines the advantages of electronics and photonics to obtain a "signal quality that is one million times greater than the one produced by the best photonic THz generator that is currently on the market," Criado said.

To create the device, the team used a very highly precise and coherent optical frequency comb. They demonstrated the generation of a flat optical frequency comb generator (OFCG) based on a single commercial vertical-cavity surface-emitting laser (VCSEL), which, besides significantly reducing the device's cost, size and consumption, offers a wide tunability range and very high phase correlation between optical modes.

"This OFCG does not need any external modulator, and it is the most energy-efficient OFCG reported to date," the team said in its paper on the work in IEEE's Photonics Technology Letters (doi: 10.1109/LPT.2013.2280700).

From this source, the researchers combined radio-frequency and photonic-electronic techniques to synthesize a very high quality THz signal.

"The quality of the signal is so high that it has not been possible to measure some of the parameters with precision; they are higher than the measurement limits of our laboratory instruments," said Criado, who is currently working on development of the commercial system. "Industrializing the laboratory prototype will be an important challenge; our objective is to provide a totally automated system that is easy for users with no specific training in this technology to operate."

The generator is projected for market launch by Luz Wavelabs in 2015. The company hopes to create a device that is easy for a layman to use, as the commerical systems currently available are much more oriented toward scientists. It also hopes the innovation will open the product for use by architects, doctors and technicians controlling industrial processes, among other applications.

From a scientific perspective, the application that has given the greatest impulse to the development of THz waves is radio astronomy.

"Since most blackbody radiation and a large quantity of molecular and intermolecular resonances are located in the area of the terahertz waves, having powerful, high-quality tools to work in this field will lead, in the future, to great advances in our understanding of the origin and function of the universe," Criado said.

The scientific observation of celestial radiation that has reached the vicinity of Earth, and the interpretation of these observations to determine the characteristics of the extraterrestrial bodies and phenomena that have emitted the radiation.